KR0131182B1 - Flexible shaft coupling - Google Patents

Abstract

The first hub, the second hub, and the first hub having a plurality of spring holes penetrating the flange in the circumferential direction and having flanges extending in the outer diameter direction at one end of the cylindrical portion, respectively, to which the electric shafts are connected. The clearance of the size necessary for shaft adjustment is installed between the flange and the second hub and the holder, and the cylindrical portion of the first hub penetrates and receives the flange of the first hub and is fixed to the flange of the second hub. In a flexural shaft joint consisting of a holder and a cylindrical coil spring which respectively penetrates the spring hole of the flange of the first hub, the cylindrical coil spring is deformed at the time of torque transmission so that the adjacent coil is connected to the flange of the second hub to connect the adjacent coil. Compressed in between, the tubular coil spring is fitted to the spring hole of the first hub at the maximum outer diameter and fits at the minimum inner diameter. Wherein there is an interference fit on a support pin provided between the flange and the holder of the second hub.

Description

Flex shaft joint

1 is a longitudinal sectional view of a flexural shaft joint showing a first embodiment of the present invention.

2 is a partial cross-sectional view of FIG. 2-2 of FIG.

3 is a longitudinal sectional view of a flexural shaft joint showing a second embodiment of the present invention.

4 is a longitudinal sectional view of a flexural shaft joint showing a third embodiment of the present invention.

5 is a diagram illustrating an eccentric adjustment action of a flexure joint of the present invention.

6 is an explanatory view of a deflection adjustment action of a flexure joint of the present invention.

7 is an explanatory diagram of an axial error adjustment action of a flexure joint of the present invention.

8 is an explanatory diagram of a test method for a cylindrical coil spring.

9 is a load bending curve showing one example of test results of a cylindrical coil spring.

10 is a torque attenuation curve that schematically shows a buffering action and a torsional vibration damping action.

11 is a longitudinal cross-sectional view showing an example in which the flexural shaft joint of the present invention is used in a granular motor system.

12 is a longitudinal sectional view showing a shaft joint connected to two sets of flexural shaft joints of the present invention.

13 is a longitudinal sectional view showing a shaft joint in which two sets of flexural shaft joints of the present invention are connected through an intermediate shaft.

14 is a longitudinal sectional view showing an example in which the bending shaft joint of the present invention is accommodated in a V-belt pulley.

15 is a longitudinal sectional view showing an example in which the flex shaft joint of the present invention is accommodated in a sprocket.

16 is a longitudinal sectional view showing a state in which the clutch is broken in the example in which the flex shaft joint of the present invention is accommodated in the air clutch.

17 is a view showing a state in which the drive shaft is in contact with the driven shaft in the air clutch shown in FIG.

18 is a partial cross-sectional view showing a brake in which the flex shaft joint of the present invention is accommodated.

19 is a longitudinal sectional view of the brake drum of the brake.

20 is a longitudinal sectional view showing an example of a torque limiter in which a flex shaft joint of the present invention is accommodated.

FIG. 21 is a longitudinal cross-sectional view of the toric limiter shown in FIG. 20; FIG.

22 is a front view of the annular cover shown in FIG.

23 is a partially enlarged cross-sectional view of the torque limiter.

* Explanation of symbols for main parts of the drawings

1: first hub 2: cylindrical part

4 flange 6 spring hole

8: keyway 11: second hub

[Background of invention]

The present invention relates to a flexure shaft joint without backlash.

One of the elastic flexural shaft joints includes a coil spring as a flexural member.

There is a bending shaft joint having a structure in which the coil spring is deformed in a direction perpendicular to the coil shaft.

The bending shaft joint of this structure has the advantage that the structure is simple and small because the spring sheet is not required, and the inertia matrix is small. As a flexible shaft joint of such a structure, there is a shaft joint disclosed in US Patent No. 4,639,237.

The shaft joint of U.S. Patent No. 4,639,237 has a flange at one end of the cylindrical portion, the first hub and the second hub to which the electric shaft is connected, and the cylindrical portion of the first hub penetrates to receive the flange of the first hub. A holder fixed to the flange of the second hub and a coil spring penetrating through a plurality of spring holes provided in the circumferential direction on the flange of the first hub, respectively. A first hub and a second hub are arranged with two flanges facing each other at intervals, and the coil spring is compressed between the flange and the holder of the second hub.

The torque is transmitted through the coil spring between the first hub and the second hub. The coil spring deforms to adjust the shaft center and absorbs the shock applied to the transmission shaft. In addition, the coil spring is fitted to the spring hole of the hub flange so that there is no backlash and the rotation angle is high.

Since the coil spring is deformed in the horizontal direction between the flange of the first hub, the flange and the second flange, and the holder, respectively, the conventional bending shaft joints generate a large stress in the coil spring, and the deformation amount of the coil spring cannot be large. As a result, axial adjustment, buffering and torsional vibration damping were small.

Thus, there has been a demand for backlash-free flexural shaft joints with greater axial adjustment, cushioning, and torsional vibration damping.

[summary]

It is an object of the present invention to provide a backlash-free flexural shaft joint having excellent axial adjustment, relaxation and torsional vibration damping.

The flexible shaft joint of the present invention has a plurality of spring holes penetrating the flange in the flange of the first hub in the circumferential direction and has a flange extending in the outer diameter direction at one end of the cylindrical portion, and the first hub connected to the electric shaft, and A holder fixed to the flange of the second hub by allowing the second hub, the cylindrical portion of the first hub to penetrate, to receive the flange of the first hub facing each other at a distance to the flange of the second hub, and the first hub; The tubular coil spring penetrates through the spring hole of the flange of each. The cylindrical coil spring is compressed between the second hub and the holder such that the coil coil deforms during torque transmission and contacts adjacent coils. The cylindrical coil spring is fitted into the spring hole of the first hub at the maximum outer diameter and is fitted to the pin supported between the flange and the holder of the second hub at the minimum inner diameter.

A gap of a size necessary for shaft adjustment is provided between the second hub and the holder fixed to the flange of the second hub and the flange of the first hub housed therein.

The torque is tightly fitted into the cylindrical coil spring and the cylindrical coil spring in the drive shaft, and is transmitted to the driven shaft in contact with the pin supported by the second hub flange and the holder, the second hub and the second hub, or vice versa. At this time, the cylindrical coil spring is compressed in the inner diameter direction of the portion to which the load of the center of the spring is applied in response to the size of the transmission torque. Moreover, the cylindrical coil spring is deformed in the direction of the spring axis, the radial direction, or inclined with respect to the spring axis and adjusted to the shaft center. The shock of the torque transmission system is absorbed and the torsional vibration is attenuated by the elastic deformation of the cylindrical coil spring and the friction of the adjacent coils.

EXAMPLE

1 and 2 illustrate a first embodiment of the present invention.

The flexible shaft joint is mainly composed of a first hub 1, a second hub 11, a holder 21, a pin 31, and a tubular coil spring 35.

The first hub 1 has a flange at one end of the cylindrical portion 2, and eight spring holes 6 are provided in the flange 4 along the circumferential direction. The cylindrical portion 2 is provided with a key groove 8, and an electric shaft is connected to the first hub 1 through the key.

As for the cylindrical part 12 of the 2nd hub 11, the flange 14 is provided in the front-end | tip, and the key groove 18 for connecting an electric shaft is excavated. The flange 14 is provided and the key groove 18 for connecting the electric shaft is dug. The pin hole 16 is provided in the end surface of the flange 14 so that the spring hole 6 of the flange 14 of the said 1st hub 1 may correspond.

The holder 21 is dish-shaped, and the hole 23 which the cylindrical part 2 of the 1st hub 1 penetrates is provided in the center part. The holder 21 is provided with a pin hole 26 so as to face the pin hole 16 of the flange 14 of the second hub 11. The holder 21 is fixed to the flange 14 of the second hub 11 by a connecting holder 28 at their outer periphery. The holder 21 houses the flange 4 of the first hub 1 facing the flange 14 of the second hub 11 at an interval. A gap of a size necessary for shaft adjustment is provided between the holder 21 fixed to the flange 14 of the second hub 11 and the flange 4 of the first hub 1 housed therein. .

Both ends of the pin 31 are inserted into the pin hole 16 of the flange 14 of the second hub 11 and the pin hole 26 of the holder 21, respectively, and the pin 31 has a second hub ( 11) and the holder 21 is supported at both ends.

The cylindrical coil spring 35 penetrates through the spring hole 6 of the flange 4 of the first hub 1.

The cylindrical coil spring 35 is heat-fitted to the spring hole 6 of the first hub 1 at the maximum outer diameter 36 and heat-fit to the pin 31 at the minimum inner diameter 37. It is.

In addition, when the torque is transmitted, the cylindrical coil spring 35 is deformed and compressed to the extent that adjacent coils come into contact with each other, and is attached between the second hub 11 and the holder 21. The cylindrical coil spring is compressed between the second hub and the holder, for example 5-15% of the free length of the spring.

The number of cylindrical coil springs depends on the size of the transfer torque, but for example 4 to 16.

The fitting of the tubular coil spring into the spring hole or pin is by heat fitting or cooling fitting.

For this reason, polishing of the maximum outer diameter part and the minimum inner diameter part of a cylindrical coil spring is also performed.

3 shows a second embodiment of the present invention. In the following embodiments, the same members as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

In this embodiment, the pin holes 43 and 46 penetrate the flange 42 and the holder 45 of the second hub 41, respectively. The connecting bolt 48 serving as the pin of the first embodiment fixes the holder 45 to the flange 42 of the second hub 41 and simultaneously holds the tubular coil spring 35.

In this embodiment, since the connecting bolt 48 also serves as the pin of Embodiment 1, the outer diameter is reduced, and the shaft joint can be miniaturized. In addition, the moment of inertia is also reduced.

4 is a third embodiment of the present invention.

An intermediate ring 57 is inserted between the second hub 51 and the holder 54. The pin hole 58 penetrates the intermediate ring 57 so as to face the pin hole 55 of the holder 54. The intermediate ring 57 is fixed to the holder 54 by a hexagon socket head bolt 59. The holder 54 and the intermediate ring 57 are integrally attached to the flange 52 of the second hub 51 by the connecting bolt 28.

In this embodiment, when the shaft joint is disassembled, the holder 54 and the intermediate ring 57 may be integrally disassembled from the second hub 52. Therefore, since the pin 31 does not need to be drawn out, it is suitable for the case where the decomposition space in the axial direction is limited.

Referring to FIG. 5 for the operation of the flexure shaft joint configured as described above, the torque is a cylindrical shape held by the first hub 1 and the first hub flange 4 to which the drive shaft is sequentially connected in the drive shaft (not shown). Coil spring 35 and tubular coil spring 35 are fitted together and driven by second hub flange 14 and pin 21 supported by cover 21 and driven shaft connected to second hub 11 ( Not shown) or vice versa. At this time, the cylindrical coil spring 35 is compressed in the inner diameter direction of the load side of the spring central portion 36 is applied in response to the size of the transmission torque. Therefore, the opposite side is elastically deformed to extend in the outer diameter direction.

The deviation of the axial center consists of an eccentric (ΔY), a declination (Δθ), and an axial error (Δ ×).

The eccentric ΔY of the transmission shaft is absorbed by deforming in the radial direction of the spring to the tubular coil spring 35 as shown in FIG. As shown in Fig. 6, the declination angle Δθ is absorbed by the cylindrical coil spring 35 being deformed in the oblique direction.

Moreover, as shown in FIG. 7, the cylindrical coil spring 35 deforms and absorbs in the spring axial direction as shown in FIG.

Next, the characteristic of the cylindrical coil spring in the torque load state of the said bending shaft joint is demonstrated.

8 shows a test method for obtaining a load-bend curve of a cylindrical coil spring.

Both ends of the pin 62 into which the cylindrical coil spring 61 is inserted are supported by the support tool 63. The pins 62 are fitted by heating at both ends of the cylindrical coil spring 61. The free length of the cylindrical coil spring 61 is 60mm, the minimum inner diameter is 35mm and the maximum outer diameter is 65mm. In the state of being compressed to 55 mm in the coil axis direction, a load is applied to the spring shaft at right angles through the pressing metal ball 64 at the maximum diameter portion of the tubular coil spring 61, that is, the central portion of the spring.

9 shows the load-bend curve. Curve A represents the results obtained by the test method and is non-linear and depicts hysteresis. The area size of the hysteresis indicates the magnitude of energy absorption by friction of adjacent coils.

Moreover, since a spring bends large in the range with a small load, deviation of a large shaft center can be adjusted. The line B is shown as a comparison and shows the test result of applying the load to the cylindrical coil spring in a direction perpendicular to the spring axis. Line B is approximately straight. In this case, there is no friction between adjacent coils, only elastic deformation. The straight line C shows the result of test by applying a load in the direction of the spring axis to a cylindrical coil spring having the same deflection at the maximum test load.

10 is a torque attenuation curve that schematically shows a buffering action and a torsional vibration damping action. Curve a shows the flexural shaft joint of the present invention, and curve b shows the rigid shaft joint, such as a gear shaft joint and a disk shaft joint, respectively. As is clear from this diagram, in the flexural joint of the present invention, the adjacent coils rub against each other, so that the shock absorbing and torsional vibration damping functions are significantly larger than those of the conventional one. In addition, the buffer action of hwimchuk joint of the invention is about 60-70% when expressed as _{T 2 / T 1 × 100%} . The torsional vibration damping effect is expressed as S ₂ / S ₁ × 100%, about 20 to 60%.

In the present invention, since the cylindrical coil spring is used for the elastic element that delivers the torque, the deformation in the direction perpendicular to the spring axis is large and the working stress is small. In particular, in the lower mid-range, the spring constant is very small, so the shaft adjustment is excellent, and the reaction force applied to the joint element by the shaft adjustment is small.

Since the cylindrical coil springs are assembled to generate friction between adjacent coils, the spring characteristics indicate nonlinear hysteresis and the spring constants at high loads can deliver very large and large torques. Therefore, the shock from the transmission shaft is absorbed by the elastic deformation of the tubular coil spring and the friction of the adjacent coil, thereby damping the torsional vibration.

As a result, it can absorb large shocks and rapidly dampen torsional vibrations.

In addition, since the cylindrical coil spring is held by both the inner and outer diameters by interference fitting, no backlash occurs. Because of this, high speed rotation is possible and high precision position control is possible.

Due to these facts, the flexible shaft joint of the present invention is applied to all applications, but is particularly suitable for equipments with heavy impact such as steel making machines, and equipments of high speed and high precision such as printing presses.

Next, an application example using the bending shaft joint of the present invention will be described.

In the following application examples, the same members as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

11 shows an example in which the flexural shaft joint of the present invention is used for a vertical axis electric system.

The bending shaft joint is arranged in a vertical position, and a driving shaft is connected to the upper second hub 11 and a driven shaft is connected to the lower first hub 1, respectively. A motor is connected to the drive shaft and a pump is connected to the driven shaft, respectively. The flange face 5 of the first hub 1 is part of the spherical surface, and the flange face 5 supports the load on the drive shaft side. When a declination occurs between the drive shaft and the driven shaft, the flange surface 15 of the second hub 11 is inclined to roll on the spherical flange surface 5 of the first hub 1, and the tubular coil spring 35 is inclined. It deforms in the oblique direction and absorbs a declination between both axes.

FIG. 12 shows an example of a bending shaft joint connecting two sets of the same shaft joint members.

In the angular joint, the flange 4 of the hub 1 is accommodated between the holder 21 and the annular cover 75. The cylindrical coil spring 35 is compressed between the holder 21 and the annular cover 75 and held in the spring hole 6 of the flange 4. The pin 31 supported by the holder 21 and the annular cover 75 penetrates through the cylindrical spring 35. Two sets of shaft joints configured in this way are connected by bolts 77 so as to be in contact with each other on the surface of the annular cover 75.

In this flexural joint, the amount of adjustment of the shaft center is doubled, and the shock absorbing and vibration damping operations are approximately doubled as compared to a set of flexural joints.

FIG. 13 shows an example of a flexible shaft joint in which two sets of shaft joint members are connected through an intermediate shaft. The shaft joint member is the same as the bending shaft joint shown in FIG. 1 and FIG.

The first hubs 1 of the two shaft joint members are connected to each other via the intermediate shaft 79 inserted into the first hub 1. Drive shafts or driven shafts are respectively connected to the second hubs 11 on both sides. By adjusting the length of the intermediate shaft 79, the interaxial distance between the drive shaft and the driven shaft can be adjusted. Improvements in the axial center adjustment amount, the shock absorbing action and the vibration damping action are larger than those of the flexural shaft joint shown in FIG. Moreover, you may arrange | position the 1st hub 1 to the outer side, and the 2nd hub 11 to the inner side, respectively.

Fig. 14 shows an example in which the bending shaft joint of the present invention is accommodated in the V belt pulley.

The V-belt groove 82 is provided in the outer periphery of the holder 81. An annular cover 84 is fixed to the holder 81 with a bolt 86, and a flange 4 of the hub 1 is accommodated between the holder 81 and the annular cover 84. As for the cylindrical coil spring 35, the pin 31 supported by the holder 81 and the annular cover 84 penetrates through the cylindrical coil spring 35. As shown in FIG. The drive shaft or the driven shaft is connected to the hub 1.

Although the V-belt pulley has been described above, the flexible shaft joint can be similarly accommodated in the flat belt pulley. With the same configuration as the V belt pulley, when the holder outer peripheral surface is a cylindrical surface without a groove, a flat belt pulley is obtained. Since the belt pulley accommodates the bending shaft joint, the belt pulley adjusts the shaft center between the belt pulley and the drive shaft or the driven shaft, and again absorbs the shock of the belt transmission system and attenuates vibration. The belt pulley with shaft adjustment, shock absorption and vibration damping can be designed in a compact size.

Fig. 15 shows an example in which the flex shaft joint of the present invention is accommodated in a chain drive sprocket. The structure of the sprocket is basically the same as the belt pulley.

In the sprocket, a gear 87 engaged with the chain is provided on the outer circumference of the holder 85.

The action and effect of this sprocket is the same as the belt pulley.

16 and 17 show an example in which the flex shaft joint of the present invention is accommodated in an air clutch.

A rim 92 having a friction surface is provided on the outer circumference of the cover 91. The holder 21 is fixed to the cover 91 with a bolt 93, and the flange 4 of the first hub 1 is accommodated between the cover 91 and the holder 21. The cylindrical coil spring 35 is held in the spring hole 6 of the flange 4 of the first hub 1 in a compressed state between the cover 91 and the holder 21.

The pin 31 supported by the cover 91 and the holder 21 penetrates the tubular coil spring 35.

The cylindrical body 96 is fixed to the flange 95 of the 2nd hub 94 by the bolt 97. As shown in FIG.

The hollow ring 99 made of rubber is fixed to the inner circumferential surface of the cylindrical body 96, and the friction material 100 is embedded in the inner circumferential surface of the hollow ring 99.

A compressed air source (not shown) is connected to the hollow ring 99. The drive shaft 102 is connected to the first hub 1, and the driven shaft 103 is connected to the second hub 94, respectively.

16 shows a state where the air clutch is disconnected. When compressed air is supplied to the hollow ring 99, as shown in FIG. 17, the hollow ring 99 expands toward the inner diameter side so that the friction material 100 comes into contact with the outer circumferential surface of the cover 91. As shown in FIG. As a result, torque is sequentially driven through the first hub 1, the tubular coil spring 35, the cover 91, the hollow ring 99, and the second hub 94 on the drive shaft 102. 103). The action and effect of this air clutch is the same as the belt pulley.

18 shows a brake in which the flex shaft joint of the present invention is accommodated.

The brake drum basically has the same structure as the bending shaft joint of FIG.

As shown in FIG. 19, the rim 108 is provided in the outer periphery of the flange 106 of the 2nd hub 105, and the outer peripheral surface of the rim 108 is an acting surface of a brake.

The holder 21 is fixed to the flange 106 of the second hub 105 by a bolt 110, and the flange 4 of the first hub 1 is received between the flange 106 and the holder 21. It is.

The cylindrical coil spring 35 is held in the spring hole 6 of the flange 4 of the first hub 1 with the second hub 105 compressed between the flange 106 and the holder 21. It is.

The pin 31 supported by the flange 106 and the holder 21 of the second hub 105 penetrates through the tubular coil spring 35. A driven shaft is connected to the first hub 1 and a drive shaft is connected to the second hub 105, respectively.

On the other hand, as shown in FIG. 18, a pair of curved first brake shoes 112 and second brake shoes 115 are connected to the bed 117 by pins 118.

The first brake shoe 112 and the second brake shoe 115 are connected through the connecting rod 120. The connecting rod 120 penetrates through the flange 113 of the first brake shoe 112, and an adjustment screw 122 is fitted to the front end thereof. A coil spring 124 is inserted between the flange 113 and the adjusting screw 122. The coil spring 124 acts to close the first brake shoe 112 and the second brake shoe 115. The hydraulic cylinder 128 is connected to the first brake shoe 112 through the driving rod 126. Driving the hydraulic cylinder 128 raises the piston rod 129 so that the brake shoe is spaced apart from the brake acting surface of the rim 108, and the brake does not operate. When the driving of the hydraulic cylinder 128 is stopped, the piston rod 129 is lowered, and the brake shoes 112 and 115 are in contact with the brake action surface of the rim 108 to operate the brake.

FIG. 20 shows an example of a torque limiter in which the flex shaft joint of the present invention is accommodated.

An annular cover 134 rotatably fitted to the second hub 131 is connected to the holder 21 by a bolt 137. The flange 4 of the first hub 1 is accommodated between the annular cover 134 and the holder 21. The cylindrical coil spring 35 is held in the spring hole 6 of the flange 4 of the first hub 1 in a compressed state between the annular cover 134 and the holder 21.

The pin 31 supported by the annular cover 134 and the holder 21 passes through the tubular coil spring 35. As shown in Figs. 21 to 23 on the side opposite to the surface to which the holder 21 of the annular cover 134 is connected, eight arc-shaped grooves 135 extending in the radial direction are spaced at regular intervals in the circumferential direction. Is installed. In addition, the movable ring 141 is attached to the second hub 131 so as to be movable in the axial direction by the sliding key 144. The movable ring 141 is provided with a roller groove 142 facing the arc-shaped groove 135 of the annular cover 134.

The roller 145 is inserted into the roller groove 142, and a part of the roller 145 is fitted into the arcuate groove 135. The disc spring 149 is inserted between the movable ring 141 and the adjusting nut 147 screwed into the second hub 131. A drive shaft is connected to the first hub 1 and a driven shaft is connected to the second hub 131, respectively. The disc spring 149 pushes the roller 145 to the groove bottom of the arcuate groove 135 via the movable ring 141.

Torque limit configured as described above, the torque from the drive shaft is the first hub 1, cylindrical coil spring 35, annular cover 134, roller 145, movable ring 141 and the second hub ( 131) is transmitted to the driven shaft via aberrations. When excessive torque is applied to the driven shaft and the torque reaches the set torque, the arcuate groove 135 of the annular cover 134 passes over the roller 145.

As a result, the engagement between the annular cover 134 and the movable ring 141 is released, and torque transmission from the drive shaft to the driven shaft is cut off.

Claims (13)

A plurality of spring holes 6 penetrating the flange 4 in the flange 4 of the first hub 1 is provided along the circumferential direction, and extends in one end of the cylindrical portion 2, 12 in the outer diameter direction ( 4 and 14, the first hub 1 and the second hub 12, the flange 4 of the first hub 1, the second hub 11 and the holder 21 to which the transmission shaft is connected, respectively. Gap between the cylinders 2 of the first hub 1 penetrates and accommodates the flange 4 of the first hub 1 to accommodate the second hub 11. Coil spring in a flexure shaft joint consisting of a holder 21 fixed to a flange 14 of the crankshaft 14 and a coil spring 35 passing through a spring hole 6 of the flange 4 of the first hub 1, respectively. Numeral 35 is a cylindrical coil spring, and the cylindrical coil spring 35 is compressed between the flange 14 of the second hub 11 and the holder 21 so that adjacent coils are deformed upon torque transmission. , Wool coat Both coil springs 35 are forcibly fitted into the spring holes 6 of the first hub 1 at the maximum outer diameter portion 36 and the flanges of the second hub 11 at the minimum inner diameter portion 37. A flexible shaft joint, characterized in that it is fitted to a pin 31 supported between the holder 14 and the holder 21. The end of the pin 31 is inserted into the bottom pin hole 16 provided in the flange 14 and the holder 21 of the second hub 11, respectively. The second hub 11 is supported by the flange 14 and the holder 21 of the second hub 11, and the bolt 28 passes through the flange 14 and the holder 21 of the second hub 11. 11) flexure shaft joint, characterized in that the holder 21 is connected. The second hub 41 and the holder 45 are connected to each other by a bolt 48 having a pin portion penetrating the flange 42 and the holder 45 of the second hub 41. A bending shaft joint, characterized in that the minimum inner diameter portion 37 of the coil spring 35 is fitted to the pin portion. 2. An annular intermediate ring (57) inserted between the first hub (1) and the second hub (51), the flange 52 of the second hub (51), the intermediate ring ( 57, the second hub 51 and the holder 54 are connected through the intermediate ring 57 by a bolt 28 passing through the peripheral portion and the holder 54, and the pin 31 is connected to the intermediate ring 57. The pin 31 ends are inserted into pin holes 55 and 58 respectively provided in the 57 and holder 54 so that the pin 31 is supported by the intermediate ring 57 and the holder 54. Flexible shaft joints. The flexible shaft joint according to claim 1, wherein the cylindrical coil spring (35) is compressed 5-15% of the spring free length between the second hub (11) and the holder (21). 2. Flexural shaft joint according to claim 1, characterized in that the tubular coil spring (35) is heat-fitted or cold-fitted to the spring bore (6) of the first hub (1) at its maximum diameter (36). The flexible shaft joint according to claim 1, wherein the tubular coil spring (35) is heat-fitted and cooled-fitted at the minimum diameter portion (37). The flexible shaft joint according to claim 1, wherein the maximum diameter portion (38) and the minimum diameter portion (37) of the cylindrical coil spring (35) are polished and polished, respectively. The bending shaft joint according to claim 1, wherein the flat surface (5) of one hub (1) has become part of a spherical surface. A plurality of spring holes 6 penetrating the flange 4 in the flange 4 of the hub 1 are provided along the circumferential direction, and the transmission shaft has a flange extending in the outer diameter direction at one end of the cylindrical portion 2. Between the hub 1, the flange 4 of the hub 1 and the holder 21 and the annular cover 75 is provided with a gap of the size necessary for the adjustment of the shaft center, the cylindrical portion of the hub (1) Two sets of joint members each comprising a holder 21 through which the two passes, and coil springs 35 passing through the spring holes 6 of the flange 4 of the hub 1, respectively. In a flexible shaft joint in which the member is connected with the annular cover surfaces in contact with each other, the coil spring 35 is a cylindrical coil spring, and the cylindrical coil spring 35 is deformed during torque transfer so that adjacent coils contact each other. 21 is compressed between the annular cover 75 and a cylindrical coil The ring 35 is forcibly fitted into the spring hole 6 of the hub 1 at the maximum outer diameter 36 and between the holder 21 and the annular cover 75 at the minimum inner diameter 37. A flexible shaft joint, which is forcibly fitted to a supported pin 31. A plurality of spring holes 6 penetrating the flange 4 in the flange 4 of the first hub 1 are provided along the circumferential direction and extend in the outer diameter direction at one end of the cylindrical portion 2, 12. And between the first hub 1 and the second hub 11, the flange 4 of the first hub 1, the second hub 11, and the holder 21 to which the transmission shaft is connected. The clearance of the size necessary for shaft adjustment is installed in the cylinder, and the cylindrical portion 2 of the first hub 1 penetrates and receives the flange 4 of the first hub 1 so as to receive the second hub 11. Two sets of joint members each comprising a holder 21 fixed to the flange 14 and a coil spring 35 passing through the spring hole 6 of the flange 4 of the first hub 1, In a flexible shaft joint in which two sets of joint members are connected through an intermediate shaft 79 inserted into the first hub 1 or the second hub 11, the coil spring 35 is a cylindrical coil spring, and a cylindrical shape. Coil spring (3) 5) is deformed during torque transfer and compressed between the flange 14 of the second hub 1 and the holder 21 so that adjacent coils come into contact with each other. The tubular coil spring 35 has a maximum outer diameter 36 ) Is fitted to the spring hole 6 of the first hub 1, and is supported between the flange 14 of the second hub 11 and the holder 21 at the minimum inner diameter 37. Flexural shaft joint, characterized in that it is fitted to the pin (31). The flange 4 of the hub 1 has a plurality of spring holes 6 passing through the flange 4 in the circumferential direction and has a flange 4 extending in the outer diameter direction at the center of the cylindrical portion 2, The hub 1 to which the electric shaft is connected, the holder 81 through which the cylindrical part 2 penetrates on one side of the hub 1, and the flange 4 of the hub 1 are accommodated on the end surface of the holder 81. In the bending shaft joint consisting of an annular cover 84 in contact with each other and a coil spring 35 passing through the spring hole 6 of the flange 4 of the hub 1, the belt contact surface 82 is provided on the outer peripheral surface of the holder 81. Is formed and the coil spring 35 is a cylindrical coil spring, and the cylindrical coil spring 35 is deformed during torque transfer and compressed between the annular cover 84 and the holder 81 so that adjacent coils contact each other. The tubular coil spring 35 is pressed against the spring hole 6 of the hub 1 at the maximum outer diameter 36. And, hwimchuk seams to a minimum inner diameter portion (37) characterized in that it is an interference fit on the pin 31 supported between the said ring-shaped cover 84 and the holder 81. The flange 4 of the hub 1 is provided with a plurality of spring holes 6 penetrating the flange 4 along the circumferential direction, the flange 4 in which the bending shaft seam extends in the center of the cylindrical portion 1 in the outer diameter direction. And a holder (85) through which the hub (1) to which the electric shaft is connected, the cylindrical portion (2) of one side of the hub (1), and the flange (4) of the hub (1) are accommodated. In the flexible shaft joint consisting of an annular cover 84 in contact with the end face and a coil spring 35 passing through the spring hole 6 of the flange 4 of the hub 1, the chain is formed on the outer peripheral surface of the holder 85. Gear 87 is engaged with the chain of the transmission is formed, the coil spring 35 is a cylindrical coil spring, the cylindrical coil spring 35 is deformed at the time of torque transmission to the annular cover to contact the adjacent coil ( 84) is compressed between the holder 85 and the tubular coil spring 35 of the hub 1 at the maximum outer diameter 36. Flexure shaft, characterized in that the spring shaft 6 is fitted to the pin 31 supported between the annular cover 84 and the holder 85 at the minimum inner diameter 37 Seam.